LED light sources have advantages of high luminous efficiency, low heat generation, electricity saving, and long lifetime, thus having more and more widely applications. LED lights will gradually replace conventional illuminative lamps like incandescent lamps and halogen lamps. With the development of LED lights, LED lights are driven toward the trend of structural miniaturization. Common LED light driving circuits in the current market use an electrolytic capacitor for filtering after rectifications of voltage inputs, and inductors or transformers are also needed to be used in circuits. Because the large volume of electrolytic capacitors occupy a larger space of driving circuits, the driving circuits are difficult to be further miniaturized. Also, the lifetime of electrolytic capacitors is greatly influenced by ambient temperature of the space of driving circuits, making electrolytic capacitors have premature failures, resulting in the shortened lifetime of the whole light. The larger volume of inductors and transformers also results in difficulties in miniaturizing driving structures.